Electric soldering iron



April 9 9- c. c. ABBOTT 1,708,995

ELECTRIC SOLDERING IRON Filed July 1926 v Inventor:

Charles C. Abbott,

cnannns c.

ABBOTT, F PITTSFIELD, MASSACHUSETTS, ASSIGNOR. TQ GENIER ELECTRICCUMPANY, A co flRATlolt OF NEW YORK.

ELECTRIC SQLDERENQ IMN.

Application filed July 6, 1928. Serial No. 120,582.

My invention relates to electric soldering irons and has for its objectthe provision of a simple, reliable and eficient device of thischaracter.

In carrying out my invention in one form 1 provide an electric heatingunit consisting of a metallic casing in which a resistance heatingelement is secured. A soldering copper is secured to one end of thecasing, while a handle is secured to the other end of the casing. Myinvention also comprehends improvements in the electrical connectionsfor the resistance heating element.

Fora more complete understanding of my invention reference should be hadto the accoinpanying drawing in which Fig. 1 is a view mainly'in sectionof an electric soldering iron embodying my invention; Fig. 2 is anenlarged sectional view showing the electric heating unit; Fig. 3 is asectional view along the line 33 of Fig. 2; Fig. A is an en larged planview of a terminal member with the resistance wire connected thereto;Fig. 5 is a sectional view of Fig. 1 taken along the line 55 looking inthe direction of the arrow while Fig. 6 is an enlarged plan view of aninsulating member used in the connection of the conductor cord to theterminals of the electric heater.

Referring to the drawing, in carrying out my invention in one form 1provide an electric heating unit comprising a metallic sheath or casing10, preferably tubular, in which a heating resistance element 11 issecured. As shown, the heating resistance 11 is a wire made of asuitable material, such as a nickel chromium alloy. It is woundhelically on a cylindrical support 12 made of suitable electricallyinsulating material, such as lava. The ends of the resistance wire aresecured to metallic terminal members 13 and 1A, which.

may be made of the same material as the resistance wire, the terminalmembers being inserted in longitudinal apertures or bores 13 and 14provided for them in the support 12. In order to provide for theconnection of the endsof the resistance wire with the terminal members13 and 14, each terminal member is provided with a longitudinal slot 15,Figs. 4 and 5, the two terminal members being identical in construction.This slot begins at one end of the terminal member and terminates justshort of the other end. The end of the resistance wire is folded over toform two or more parallel lengths which are twisted together, asindicated by the numeral 16. As shown, three lengths are twistedtogether. This twisted portion 16 is placed in the groove 15 and thenthe side walls of the groove are pressed together or peened over anintermediate section of the twisted ortion, as indicated at 17 and 18.The en s of the twisted portion project from the peened over walls ofthe groove, and, due to the constriction of the intermediate length,efiectively secure the twisted portion in place. As connected with theterminal member 1 1, the resistance wire extends from the open end ofthe groove, but in the terminal member 13 the twisted portion 16 isreversed so that the wire passes out laterally from the opposite end ofthe groove, as shown in Fig. 2.

ln assembling the resistance wire and terminals on the support 12, theresistance wire is secured to the terminal 14, and the terminal 14inserted in its aperture 14$, the resistance wire being laid in alongitudinal groove 19 provided for it in the support 12 and brought tothe opposite end of the support where it is laid in a cross groove 20 inthe support and brought out at the opposite side. The resist ance wireis then wound helically on the support toward the opposite end andsufficient slack is left in the resistance wire after the windingoperation to permit the terminal 13 to be connected as previouslydescribed and then inserted in its aperture 13 in the support, theresistance wire extending through a longitudinal slot 21 in the support.After the terminal 13 has been put in place the re sistance wire istightened by twisting the terminal one or more revolutionawhereby one ormore turns of the resistance wire are wound around the terminal 18 totake up the slack. The edges of the groove 15 are rounded 0d at 15 and15 at the region where the wire is brought out laterally, in connectionwith terminal member 13, so that the wire will not be injured when woundon to take up the slack. This form of connection provides a veryreliable mechanical and electical joint and also allows the resistor tobe readily assembled on the support 12.

The oore'12 with the resistance wire thereon is embedded in the sheath10 in powdered heat refractory insulatin material 22, such as magnesiumoxide w ich is preferably compacted so as to secure the core and heatingresistance in' place and also to increase, the heat conductivity of thepowdered me- 26 and 27 of the terminal members.

terial. As shown in the drawing, the turns of the resistance wire aresuitably spaced apart on the core, the powdered insulating materialbeing packed between the turns. This compacting operation may be carriedout in any suitable manner, for example, by reducing the diameter of thesheath, as by swaging or rolling, after the unit has been assembled.

The end of the sheath opposite the terminal members 13 and 14 is closedby means of a metallic washer 23, the end of the sheath being spun overto secure the washer in place. In the opposite or terminal end of thesheath is a washer 24 made of insulating material, such as mica, and aporcelain insulator 25, apertures being provided in the the washer andinsulator for the protruding end lengths To improve their flexibilitythe lengths 26 and 27 may be made of twisted wire. As shown, theseprotruding ends or terminals are somewhat smaller than the terminalmember portions inside the unit, a shoulder being thereby formed at thejunction of the two portions on which the insulating washer 24 isseated. The end of the sheath 10 is spun over a shoul der 28 provided onthe insulator 25. In addition to acting as an insulator, the washer 24acts as a cushion or bufi'er to prevent cracking of the porcelaininsulator from the end pressure caused by the swaging operairon.

The soldering copper 29 is secured directly to the sheath 10, and asshown, the sheath is provided with threads 30, and the soldering copper29 with a tapped bore adapted to receive the threaded portion of thesheath, as shown in Fig. 1. The screw threaded engagement between thesoldering copper and the sheath provides a good thermal contact betweenthese parts so that heat is conducted freely to the soldering copper.Preferably a fairly loose fit is provided bet-ween the soldering copper29 and the sheath so that the soldering copper may be removed easilyeven after oxidation of the threads. This does not appreciably affectthe thermal contact since a good contact is obtained between the sidesof the threads when the sheath strikes the bottom of the bore. Thisconduction of heat is further improved by the fact that the solderingcopper extends throughout the greater part of the length of the casing10. It will further be observed that the heating element 11 extends froma point adjacent the left hand end of the casing 10, as viewed in Fig.2, throughout the greater part of the length of the casing, thesoldering copper being substantially coextensive with the heatingelement.

The sheath 10 is secured to a handle 31 by means of a helically shapedmember 32, helical V shaped grooves 33 and 34 being provided in thesheath and the handle respectively to receive one or more end turns ofthe member 32. The member 32 is made of spring steel or other resilientmaterial so that the end turns expand slightly when screwed on thesheath and the handle. It will be observed, however, that any attempt totwist the member 32 in the opposite direction to remove it, serves onlyto further contract the end turns and secure it more firmly in place. Inorder to facilitate the removal of the member 32 from the sheath 10,this end is beveled in the manner indicated in Fig. 3 so that asubstantially V shaped space 35 is formed with bottom of the groove. Apointed tool, such as a screw driver, may be inserted in I this spaceand used as a lever to lift the end of member 32 and Work it back outalong the groove. Preferably the helical member 32 is V shaped on itsinner side so as to fit into V shaped grooves in the sheath and thehandle.- The threads 30 are preferably formed or cut in the sheath 10after the heating unit is assembled and compacted, the sheath beingoriginally of sufficient thickness to provide for them.

The protruding end lengths 26 and 27 of the terminal members arethreaded through cylindrical porcelain insulators 36 each of which isprovided with two parallel holes 36 and 36" adapted to receive thelengths 26 and 27. As shown in Fig. 2, the insulators 36 are eachprovided with a concave surface at one end and with a convex surface atthe other end, the convex surface of one insulator fitting into theconcave surface of the adjoining insulator. The outer end of theinsulator 25 is also provided with a convex surface over which theadjacent insulator 36 fits. This arrangement of convex and concavesurfaces serves to interlock the various insulators and secure themagainst lateral displacement. By means of the insulators 36 it will beob served that an insulating bushing is formed around the terminals 26and 27, which bushin extends centrally of the member 32 into a ore 37provided in the handle 31 Where electrical connections are made betweenthe ends of the terminals and an insulated twin conductor 38. This twinconductor extends through a somewhat smaller bore 37 in the handle andit is provided with a suitable connection device, such as a plug bymeans of which the soldering iron can be conveniently connected to anelectrical supply circuit.

In making the connection between the ends of the terminals and the twinconductor 38, a strip 39 of electrically insulating material such asfibre, is used. Referring to Fig. 6, this strip is cut out at one end at40 so as to fit over the convex surface of the end insulator. It is alsoprovided with pairs of oppositely disposed notches 41 and 42, with twoapertures 43 and 44, and with a concave edge 45 at the opposite end. Asshown in Fig. 1, the strip 39 is placed between the two terhandle, saidmember and said handle being minals to form twisted joints 46. Beforethe twisted connections are made, the insulated conductors are threadedthrough the two holes 43 and 44, each being passed through a hole,whereby the twisted conductor is se-' cured to the strip 39. The twoinsulated conductors are seated in the concave end 45 of the strip 39.The ends of the terminals are secured to the strip 39 by tying them witha cord made of a suitable insulating material, such as linen, the cordbeing wrapped around the strip in the pair of notches 42, as indicated.

by reference numeral 48. The twisted joints 46 are folded over on thestrip and secured by a wrapping 49 of cord which is laid in the pair ofnotches 41. The insulator strip 39 sepa rates the twisted connections 46and insulates them from each other, while the wrappings I of cord'securethe connections to the strip and prevent the strip from slipping. Anypull which might be accidentally or otherwise applied to the twinconductor cord is applied directly to the stri 39, the end of whichrests against the shoul er formed at the junction of bores 37 and 37,since the cord is secured to the strip, and cannot be transmitted to thetwisted connections.

While I have described my invention as embodied in concrete form and asoperating in a specific manner in accordance with theprovisions of thepatent statutes, it should be understood that I do not limit myinvention thereto, since various modifications thereof will suggestthemselves to those skilled in the art without departing from the spiritof my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. An electric soldering iron comprising a metallic cylindrical memberprovided with a bore, a handle secured to one end of said member, asoldering copper secured to the other end of said member surroundingsaid member thoughout the greater part of its length, and heating meansin said bore.

2. An electric soldering iron comprising a hollow metallic member, ahandle, a helical member connecting said member with said member, asoldering copper secured to and slubstantially surrounding said metallicmember, and heating means in said metallic member.

3. An electric soldering iron comprising a hollow metallic member, anelectric heating element in said member extending from. a point adjacentone end throughout the greater portion of said member, a solderingcopper secured to said member at said end extending substantiallycoextensively with said heating element and a handle secured to theother end of said member.

4. A soldering iron comprising a hollow metallic member, a handle, ahelical member connecting said member with said handle, said member andsaid handle being provided with grooves at one end to receive saidhelical member, and said member being threaded throughout substantiallythe remainder of its length, a soldering copper provided with a threadedbore fitting on the threaded portion of said member, and heating meanssecured within said hollow metallic member.

5. A soldering iron comprising a soldering copper, a resistance heatingelement therefor, a handle attached to said copper,said handle beingprovided with a longitudinal bore having an enlarged portion in the endadjacent said copper whereby a shoulder is formed within said bore, astrip of insulating material in said enlarged portion provided withapertures and resting against said shoulder, an insulated conductorextending through said bore threaded back and forth through saidapertures, and a connection between said conductor and said heatingelement.

6. A soldering iron comprising a metallic member, a resistance heatingelement therefor, a handle secured to said metallic member, said handlebeing provided with a longitudinal bore having an enlarged portion inthe end adjacent said metallic member whereby a shoulder is formedwithin said bore, a

strip of insulating material in said enlarged tures, and a connectionbetween said con uc- I tor and said heating element.

In witness whereof, I have hereunto set my hand this 29th day of June,1926.

CHARLES C. ABBOTT.

